LoongArch: Fixup do_ri csr_era

[PATCH v3] LoongArch: Fixup do_ri csr_era

Posted by Jun Yi 3 years, 6 months ago

csr_era of pt_regs in do_ri should not add 4 to point to the
next instruction.

Signed-off-by: Jun Yi <yijun@loongson.cn>
---
 arch/loongarch/kernel/traps.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index aa1c95aaf595..ec888eda3d45 100644
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -477,8 +477,6 @@ asmlinkage void noinstr do_ri(struct pt_regs *regs)
 
 	die_if_kernel("Reserved instruction in kernel code", regs);
 
-	compute_return_era(regs);
-
 	if (unlikely(get_user(opcode, era) < 0)) {
 		status = SIGSEGV;
 		current->thread.error_code = 1;
-- 
2.31.1

Re: [PATCH v3] LoongArch: Fixup do_ri csr_era

Posted by Guo Ren 3 years, 6 months ago

On Mon, Sep 26, 2022 at 8:27 PM Jun Yi <yijun@loongson.cn> wrote:
>
> csr_era of pt_regs in do_ri should not add 4 to point to the
> next instruction.
The comment does not make sense. I think it wants to skip some
instructions, but your patch broke that.

>
> Signed-off-by: Jun Yi <yijun@loongson.cn>
> ---
>  arch/loongarch/kernel/traps.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
> index aa1c95aaf595..ec888eda3d45 100644
> --- a/arch/loongarch/kernel/traps.c
> +++ b/arch/loongarch/kernel/traps.c
> @@ -477,8 +477,6 @@ asmlinkage void noinstr do_ri(struct pt_regs *regs)
>
>         die_if_kernel("Reserved instruction in kernel code", regs);
>
> -       compute_return_era(regs);
> -
>         if (unlikely(get_user(opcode, era) < 0)) {
>                 status = SIGSEGV;
>                 current->thread.error_code = 1;
> --
> 2.31.1
>


-- 
Best Regards
 Guo Ren

Re: [PATCH v3] LoongArch: Fixup do_ri csr_era

Posted by Jun Yi 3 years, 6 months ago

do_ri is porting from mips, mipsr6 use do_ri to emulate some fp 
instructions, but Loongarch do not need to emulate these instructions.

And the regs->csr_era be always recovered to ths old_era = 
regs->csr_era, so the compute_return_era is useless.

On 9/27/22 07:41, Guo Ren wrote:
> On Mon, Sep 26, 2022 at 8:27 PM Jun Yi <yijun@loongson.cn> wrote:
>>
>> csr_era of pt_regs in do_ri should not add 4 to point to the
>> next instruction.
> The comment does not make sense. I think it wants to skip some
> instructions, but your patch broke that.
> 
>>
>> Signed-off-by: Jun Yi <yijun@loongson.cn>
>> ---
>>   arch/loongarch/kernel/traps.c | 2 --
>>   1 file changed, 2 deletions(-)
>>
>> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
>> index aa1c95aaf595..ec888eda3d45 100644
>> --- a/arch/loongarch/kernel/traps.c
>> +++ b/arch/loongarch/kernel/traps.c
>> @@ -477,8 +477,6 @@ asmlinkage void noinstr do_ri(struct pt_regs *regs)
>>
>>          die_if_kernel("Reserved instruction in kernel code", regs);
>>
>> -       compute_return_era(regs);
>> -
>>          if (unlikely(get_user(opcode, era) < 0)) {
>>                  status = SIGSEGV;
>>                  current->thread.error_code = 1;
>> --
>> 2.31.1
>>
> 
>

Re: [PATCH v3] LoongArch: Fixup do_ri csr_era

Posted by Huacai Chen 3 years, 6 months ago

Hi, all,

I clean up do_ri() further based on this patch [1], thanks.

[1] https://lore.kernel.org/loongarch/20220927045820.2770062-1-chenhuacai@loongson.cn/T/#u


On Tue, Sep 27, 2022 at 11:10 AM Jun Yi <yijun@loongson.cn> wrote:
>
> do_ri is porting from mips, mipsr6 use do_ri to emulate some fp
> instructions, but Loongarch do not need to emulate these instructions.
>
> And the regs->csr_era be always recovered to ths old_era =
> regs->csr_era, so the compute_return_era is useless.
>
> On 9/27/22 07:41, Guo Ren wrote:
> > On Mon, Sep 26, 2022 at 8:27 PM Jun Yi <yijun@loongson.cn> wrote:
> >>
> >> csr_era of pt_regs in do_ri should not add 4 to point to the
> >> next instruction.
> > The comment does not make sense. I think it wants to skip some
> > instructions, but your patch broke that.
> >
> >>
> >> Signed-off-by: Jun Yi <yijun@loongson.cn>
> >> ---
> >>   arch/loongarch/kernel/traps.c | 2 --
> >>   1 file changed, 2 deletions(-)
> >>
> >> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
> >> index aa1c95aaf595..ec888eda3d45 100644
> >> --- a/arch/loongarch/kernel/traps.c
> >> +++ b/arch/loongarch/kernel/traps.c
> >> @@ -477,8 +477,6 @@ asmlinkage void noinstr do_ri(struct pt_regs *regs)
> >>
> >>          die_if_kernel("Reserved instruction in kernel code", regs);
> >>
> >> -       compute_return_era(regs);
> >> -
> >>          if (unlikely(get_user(opcode, era) < 0)) {
> >>                  status = SIGSEGV;
> >>                  current->thread.error_code = 1;
> >> --
> >> 2.31.1
> >>
> >
> >
>